From: Patrick Bellasi <patrick.bellasi@arm.com>
To: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Quentin Perret <quentin.perret@arm.com>,
Thara Gopinath <thara.gopinath@linaro.org>,
linux-pm@vger.kernel.org,
Morten Rasmussen <morten.rasmussen@arm.com>,
Chris Redpath <chris.redpath@arm.com>,
Valentin Schneider <valentin.schneider@arm.com>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Todd Kjos <tkjos@google.com>, Joel Fernandes <joelaf@google.com>
Subject: Re: [RFC PATCH 4/6] sched/fair: Introduce an energy estimation helper function
Date: Wed, 21 Mar 2018 12:39:21 +0000 [thread overview]
Message-ID: <20180321123921.GB13951@e110439-lin> (raw)
In-Reply-To: <20180320094312.24081-5-dietmar.eggemann@arm.com>
On 20-Mar 09:43, Dietmar Eggemann wrote:
> From: Quentin Perret <quentin.perret@arm.com>
[...]
> +static unsigned long compute_energy(struct task_struct *p, int dst_cpu)
> +{
> + unsigned long util, fdom_max_util;
> + struct capacity_state *cs;
> + unsigned long energy = 0;
> + struct freq_domain *fdom;
> + int cpu;
> +
> + for_each_freq_domain(fdom) {
> + fdom_max_util = 0;
> + for_each_cpu_and(cpu, &(fdom->span), cpu_online_mask) {
> + util = cpu_util_next(cpu, p, dst_cpu);
Would be nice to find a way to cache all these util and reuse them
below... even just to ensure data consistency between the "cs"
computation and its usage...
> + fdom_max_util = max(util, fdom_max_util);
> + }
> +
> + /*
> + * Here we assume that the capacity states of CPUs belonging to
> + * the same frequency domains are shared. Hence, we look at the
> + * capacity state of the first CPU and re-use it for all.
> + */
> + cpu = cpumask_first(&(fdom->span));
> + cs = find_cap_state(cpu, fdom_max_util);
^^^^
The above code could theoretically return NULL, although likely EAS is
completely disabled if em->nb_cap_states == 0, right?
If that's the case then, in the previous function, you can certainly
avoid the initialization of *cs and maybe also add an explicit:
BUG_ON(em->nb_cap_states == 0);
which helps even just as "in code documentation".
But, I'm not sure if maintainers like BUG_ON in scheduler code :)
> +
> + /*
> + * The energy consumed by each CPU is derived from the power
^
Should we make more explicit that this is just the "active" energy
consumed?
> + * it dissipates at the expected OPP and its percentage of
> + * busy time.
> + */
> + for_each_cpu_and(cpu, &(fdom->span), cpu_online_mask) {
> + util = cpu_util_next(cpu, p, dst_cpu);
> + energy += cs->power * util / cs->cap;
> + }
> + }
nit-pick: empty line before return?
> + return energy;
> +}
> +
> /*
> * select_task_rq_fair: Select target runqueue for the waking task in domains
> * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE,
> --
> 2.11.0
>
--
#include <best/regards.h>
Patrick Bellasi
next prev parent reply other threads:[~2018-03-21 12:39 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-20 9:43 [RFC PATCH 0/6] Energy Aware Scheduling Dietmar Eggemann
2018-03-20 9:43 ` [RFC PATCH 1/6] sched/fair: Create util_fits_capacity() Dietmar Eggemann
2018-03-20 9:43 ` [RFC PATCH 2/6] sched: Introduce energy models of CPUs Dietmar Eggemann
2018-03-20 9:52 ` Greg Kroah-Hartman
2018-03-21 0:45 ` Quentin Perret
2018-03-25 13:48 ` Quentin Perret
2018-03-26 22:26 ` Dietmar Eggemann
2018-04-09 12:01 ` Peter Zijlstra
2018-04-09 13:45 ` Quentin Perret
2018-04-09 15:32 ` Peter Zijlstra
2018-04-09 16:42 ` Quentin Perret
2018-04-10 6:55 ` Rafael J. Wysocki
2018-04-10 9:31 ` Quentin Perret
2018-04-10 10:20 ` Rafael J. Wysocki
2018-03-20 9:43 ` [RFC PATCH 3/6] sched: Add over-utilization/tipping point indicator Dietmar Eggemann
2018-04-09 9:40 ` Peter Zijlstra
2018-04-09 9:47 ` Peter Zijlstra
2018-04-09 9:53 ` Dietmar Eggemann
2018-04-09 11:49 ` Peter Zijlstra
2018-03-20 9:43 ` [RFC PATCH 4/6] sched/fair: Introduce an energy estimation helper function Dietmar Eggemann
2018-03-21 9:04 ` Juri Lelli
2018-03-21 12:26 ` Patrick Bellasi
2018-03-21 12:59 ` Juri Lelli
2018-03-21 13:55 ` Quentin Perret
2018-03-21 15:15 ` Juri Lelli
2018-03-21 16:26 ` Morten Rasmussen
2018-03-21 17:02 ` Juri Lelli
2018-03-21 14:02 ` Quentin Perret
2018-03-21 21:15 ` Dietmar Eggemann
2018-03-21 12:39 ` Patrick Bellasi [this message]
2018-03-21 14:26 ` Quentin Perret
2018-03-21 14:50 ` Juri Lelli
2018-03-21 15:54 ` Patrick Bellasi
2018-03-22 5:05 ` Quentin Perret
2018-03-20 9:43 ` [RFC PATCH 5/6] sched/fair: Select an energy-efficient CPU on task wake-up Dietmar Eggemann
2018-03-21 15:35 ` Patrick Bellasi
2018-03-22 20:10 ` Joel Fernandes
2018-03-23 15:47 ` Morten Rasmussen
2018-03-24 1:13 ` Joel Fernandes
2018-03-24 1:34 ` Quentin Perret
2018-03-24 6:06 ` Joel Fernandes
2018-03-24 1:22 ` Quentin Perret
2018-03-25 1:52 ` Quentin Perret
2018-03-22 16:27 ` Joel Fernandes
2018-03-22 18:06 ` Patrick Bellasi
2018-03-22 20:19 ` Joel Fernandes
2018-03-24 1:47 ` Quentin Perret
2018-03-25 0:12 ` Joel Fernandes
2018-03-23 16:00 ` Morten Rasmussen
2018-03-24 0:36 ` Joel Fernandes
2018-03-25 1:38 ` Quentin Perret
2018-03-20 9:43 ` [RFC PATCH 6/6] drivers: base: arch_topology.c: Enable EAS for arm/arm64 platforms Dietmar Eggemann
2018-03-20 9:49 ` Greg Kroah-Hartman
2018-03-20 15:20 ` Dietmar Eggemann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180321123921.GB13951@e110439-lin \
--to=patrick.bellasi@arm.com \
--cc=chris.redpath@arm.com \
--cc=dietmar.eggemann@arm.com \
--cc=gregkh@linuxfoundation.org \
--cc=joelaf@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=morten.rasmussen@arm.com \
--cc=peterz@infradead.org \
--cc=quentin.perret@arm.com \
--cc=rjw@rjwysocki.net \
--cc=thara.gopinath@linaro.org \
--cc=tkjos@google.com \
--cc=valentin.schneider@arm.com \
--cc=vincent.guittot@linaro.org \
--cc=viresh.kumar@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).